Conventionally, in a semiconductor device manufacturing process, various plasma processes such as an etching process and a film forming process are performed on a substrate such as a semiconductor wafer by using plasma. In such a semiconductor device manufacturing process, e.g., in a manufacturing process of a NAND type flash memory, it has been known to form a step-shaped structure by performing a plasma etching process and a mask trimming process on a multilayer film that has two kinds of films each having a different permittivity. As the multilayer film, for example, an insulating film and a conductive film are alternately layered (see, for example, Patent Document 1).
Patent Document 1: Japanese Patent Laid-open Publication No. 2009-170661
However, in the aforementioned semiconductor device manufacturing process for forming the step-shaped structure in the multilayer film formed by alternately layering two kinds of layers each having a different permittivity, for example, an insulating film and a conductive film, since the number of processes that need to be performed is great, manufacturing efficiency is deteriorated. Further, it has been difficult to appropriately form a good step-shaped structure having multiple step-shaped portions due to deposits or the like.